A conventional 35 mm film cartridge, such as manufactured by Eastman Kodak Company, comprises a light-tight housing and an unexposed filmstrip. The filmstrip is supported in a roll on a rotatable spool inside the light-tight housing and has a film leader that protrudes outwardly several inches through a light-trapping slit in the housing.
A typical camera intended to be used with the conventional 35 mm film cartridge includes a cartridge receiving chamber, a film take-up chamber, and a backframe opening. The backframe opening is located between the cartridge receiving chamber and the film take-up chamber, opposite a taking lens and a shutter, for exposing successive sections of the filmstrip (not including the protruding film leader). To load the film cartridge into the camera, a rear door of the camera is opened to uncover the cartridge receiving chamber, the backframe opening, and the film take-up chamber. Then the film cartridge is placed in the cartridge-receiving chamber and substantially simultaneously the protruding film leader is placed over the backframe opening and partway into the film take-up chamber. The protruding film leader is laid on one of a pair of parallel film rails at respective sides of the backframe opening, to be engaged by a metering sprocket which projects from an opening in the one rail. When the rear door is closed, the metering sprocket can be rotated in engagement with the filmstrip to advance successive sections of the filmstrip across the backframe opening.
Another camera to be used with the conventional 35 mm cartridge is disclosed in commonly assigned prior art U.S. Pat. No. 5,493,358 issued Feb. 20, 1996. The camera includes a cartridge receiving chamber, a film take-up chamber, and a backframe opening. A rear cover is fixed over the backframe opening and the film take-up chamber to prevent direct access to them. To load the film cartridge into the camera, a rear door independent of the rear cover is opened to uncover the cartridge receiving chamber. A light-trapping film slit is located between the cartridge receiving chamber and the backframe opening to permit the protruding film leader to be longitudinally inserted through the film slit from the cartridge receiving chamber across the backframe opening and to the film take-up chamber, as the film cartridge is placed in the cartridge receiving chamber. When the rear door is opened, it retracts a metering sprocket from an operative position for engaging the protruding film leader to permit the protruding film leader to be longitudinally inserted through the film slit from the cartridge receiving chamber across the backframe opening and to the film take-up chamber. Conversely, when the rear door is closed, it allows the metering sprocket to be returned via a spring to the operative position for engaging the filmstrip.